Production of pyrazolone azo dyes



Patented Jan. 4, 1949 John David Kendall and Douglas James Fry,.

Ilford, England, assignors to Ilford Limited, Ilford, Essex, England, aBritish company No Drawing. Application November 2-9, 1945, Se-

rial No. 631,792. In Great Britain December 1,

6 Claims.

This invention relates to the production of azo dyestuffs.

When a compound containing a reactive methylene group, i. e. a compoundwhich may be represented by the general formula R1-CH2--R2 (where R1 andR2 are organic groupings at least one of which contains a group adjacentto the CH2 group which renders the CH2 group reactive) and which iscapable of forming a sodium derivative, is converted to a mono alkali,e. g. sodium, salt and reacted with a monohalogenated acetic acid orester, i. e., a compound of the formula XCH2.COOR3 (where X is a halogenatom and R3 is a hydrogen or hydrocarbon group), a reaction takes placeaccording to the following equation:

R1 sodium ethoxide CH2 XCH2COOR3 R2 CHCH2C0OR3 021150?! NaX Reaction! Inthis equation the formation of the sodium derivative is efiected in situby carrying out the reaction in the presence of sodium ethoxide.

It has now been discovered that when a compound of the formulaCH-CH2COOR3 R2 is reacted in the presence of strong alkali with at leasttwo molecular equivalents of a diazonium compound (e. g. a compound ofthe formula R4N2Cl, Where R4 is an aryl residue), reaction takes placewith the elimination of one of the groups R1 and R2 and the formation ofan azo dyestufi, thus:

R\ alkali OHCH2G0 0R3 201N211; -7

R 2-C--C N,=N-R 4 \N i Reaction 2 t. In these formulae it has beenassumed that in retherefore,

zonium compound with the condensation product;- of a mono alkali-metalderivative of a compound containing a reactive methylene group with amonohalogenated acetic acid or ester, the said reaction being efiectedin strong alkaline solution.

and the said diazonium compound being present in a proportion of atleast two molecular equivalents per molecular equivalent of'the'condensation product. p

The term molecular equivalent is to be understood as meaning inolecularequivalent per diazo group. Thus where the diazonium compound containsmore than one reactive diazo grouping, the quantity used should becorrespondingly decreased. For example, a diazonium compound containingtwo diazo groupings should be used in a proportion of at least onemolecular weight per molecular weight of the condensation product, andso on.

Examples of reagents suitable for producing the initial condensationproduct are, as the reactive methylene compound, compounds such asmalonic ester, acetoacetic ester, cyanacetic ester, acetyl acetone, or aderivative such as aceto-acetanilide in which the reactive methylenegroup is still present and, as the monohalogenated acetic acid or ester,chloracetic acid or chloracetic ethyl ester. The condensation should beeffected with the reactive methylene compound in the form-of its monoalkali-metal salt, and this can be achieved by effecting thecondensation in the presence of an alkali-metal ethoxide, e. g. sodiumethoxide. As examples of the products obtained using chloracetic ethylester, there are:

(a) From malonic ester the compound C155. 0 O (D) From acetoacetic ethylester the compound cm. 0 o CH-CH:C 0 O CzHs 0,115.0 o o OIL-Cure o 00,115

0,11,. 0 o o (d) From acetyl acetone the compound CH2. 6 O

' CH-CHz-C o 0 0,11,

0 Ha.0 0 (e) From acetoacetanilide the compound CH3. c o

oH-oH,-o o 0 01135 C GHt-NH. G O

(c) From cyanacetic ethyl ester the compound To produce the azo dyestufiin accordance with this invention, the condensation product is treatedwith the diazonium compound, in the presence of strong alkali, thereaction solution preferably being kept cold. Suitable strong alkalisare caustic soda, caustic potash and sodium ethoxide. and the like.Reaction then takes place at the CH grouping, one of the twosubstituents attached thereto in the original reactive methylenecompound being displaced and the compound ringcloses. For example, inthe case of the products of (a) and (d) above, one of the two similargroupings attached to the CH grouping is displaced; in the case of theproduct of (b) and (e) 2. 01-1300 grouping is displaced, and in the caseof the product of (c) a COOCzI-Is grouping is displaced. The azodyestufi thus formed is readily separated from the reaction mixture.

Typical azo dyestufis which may be produced by the process of thisinvention, using benzene diazonium chloride as a typical diazoniumcompound, are:

From the product'of (a) and (b) the compound From the product of (d) thecompound CH3.C OC---CN=N-CH5 t at.

From the product of (e) the compound Where a tetrazotised diamine isemployed the products apparently conform to the formula:

where R4 is a divalent aromatic residue, R1 has the meaning assigned toit above, and a: is a positive integer.

The products are sometimes slightly contaminated with pyrazole-5-ones,the specific production of which is described in co-pending applicationSerial Number 631,791 filed November 29. 1945, but are usually lessfreely soluble in alkali than the pyrazole-5-ones and can thus bereadily separated.

Whilst benzene diazonium chloride has been instanced above as a suitablediazonium compound, all the Well known diazonium compounds can besimilarly employed. As representative examples of suitable diazoniumcompounds there may be mentioned the diazonium chlorides derived fromthe following amines: aniline, toluidine, xylidine, naphthionic acid,a-llaDhthylamine, S-naphthylamine, p-aminobenzyl dim ethylamine,m-aminophenyl dimethylamine, mnitraniline, p-aminophenol, sulphanilicacid, the various amino naphthol sulphonic acids, amino azo benzene andits sulphonic acids, and diamines, e. g. benzidine, tolidines,p.p-diamino, stilbene, p.p-diamino diphenylamine, pp-diamino carbazole,p.p-diamino fluorene, p.p-diamino azobenzene, p-phenylene diamine, 1:4and 1:5 diamino naphthalenes, dehydrothio p-toluidine and its sulphonicacid, and amino anthraquinones, e. g. 1.5-diamino anthraquinone. Otherdiazo compounds commonly used in azo dye formation may also be employed.

The following examples serve to illustrate the invention:

EXAMPLE 1 Preparation of tartrazzne Sulphanilic acid (T16 mol) wasdissolved in 200 cc. of 2.5% sodium carbonate solution by warming. Thesolution was cooled to 0 C. and sodium nitrite (1% mol) added. Theresulting solution was poured into a mixture of 20 cc. concentratedhydrochloric acid and 100 gms. ice. After stirring for ten minutes thesuspension was added to a solution of ethyl aceto succinate /20 mol) in40 cc. caustic soda solution (5 N). After stirring for two hourssuflicient sodium chloride was added to saturate the solution, whereuponthe product precipitated. This was filtered off and hydrolyzed byboiling with cc. of caustic soda solution (2.5 N) for one hour. Oncooling the tartrazine separated and was purified by washin withice-cold water and boiling out with ethyl alcohol.

EXAMPLE 2 Preparation of 4-oz-7ZLZIJhthZ/ld20-1-oc7Z0tphih1/l3-carbethoacy-5-pyrazolone A solution of a-naphthylamine mol) in 50 cc.5 N hydrochloric acid was cooled in ice and diazotized by the additionof an aqueous solution of sodium nitrite 6 mol). After standing for halfan hour the diazonium solution was added, with cooling and stirring, toa solution of ethyl acetosuccinate /2o mol) in 50 cc. 20% sodiumhydroxide solution. The mixture was allowed to stand overnight tocomplete the reaction and the dye was then filtered off and washed withwater. After recrystallising from ethyl acetate the dye was obtained assmall deep maroon crystals. Melting point C. with decomposition.

EXAMPLE 3 Preparation of 4-B-naphthylazo-1-B-naphthyl-3-carbethoxy-5-;oyra2olone Preparation of 4 p sulphonamidobenzeneaew 1-psuplhonamidophenyl 3 carbethoazy 5- pyrazolone Prepared as in Example 2using p-aminobenzenesulphonamide in place of the oz-llZLPhthYlamine. Theproduct crystallised from methyl alcohol as small brick-wed crystals,melting point-208 C.' with decomposition.

Eiwlrnzr 5:

Preparation of: dye" of. the probable formula:

o o o 0 02115 Prepared as in Example 2 using amlnoazobenzene in place ofa-naphthylamine. Recrystallised from methyl alcohol the product had amelting point 198 C. With decomposition.

EXAMPLE 6 Preparation of 4-benzenea20-1-p henyl-3-acetyl- S-pyrazolonePrepared as in Example 2 using aniline inxplace I of a-naphthylamine andethyl flB-diacetyl': propionate (March, Qompt... Bend... vol. l30,p...1w193) in place of ethyl .acetosuccinate. Recrystallised from ethylacetate as small brownish-red crystals, meltingpoint 182 C.,Withdecomposition.

EXAMPLE '7 Preparation of 4:-benaeneazml-phenylea-cyan- 5-pymz0lonePrepared as in Example 2 using aniline in place of e-naphthylamine andethyl cyansuccinate (Haller and Barthe, ComptRend vol. 106 page. 1413)in place of ethyl acetosuocinate. The product consisted of small orangecrystals. Melting point 152 C. with decomposition.

EXAMPLE 8' Preparation of dye of the probable formula:

sodium carbonate solutionandth'eextracts aciditied and filtered. Theprecipitated compound is recrystallised from benzene, 'meltin-gpoint 1566. l

EXAMPLE 9 Preparation of 4- (i.ksulphonapittiialeneazb) -'1-' (1-suZphonaphthyZ) 3 carbethoxy 5 pyiazolone A solution of2-naphthylamine-l-sulphonic acid sodium salt (1% mol) and sodium nitritemol) in 200 cc. water was poured into a mixture of gm. ice and 20 cc.concentrated hydrochloric acid. After standing for half an hour thesuspension of the diazo-sulphonate was added toasolution of ethylacetosuccinate mol).

in 50 cc. 20% sodiumhydroxide solution, with cooling and stirring. Thedye was isolated by salting-out. The dye was recrystallised from aqueousspirit as small. orange crystals. Melting point about 200 C. withdecomposition.

EXAMPLE 10 Preparation of4-p-ca1'lzozrybenzeneaeo-1-pcarboxyphenyl-3-carb thomy- 5 myraaoloneSodium nitrite 6 mol) was added to a solution .1 of p-aminobenzoic acid(Te mol) in 100 cc. N sodium carbonate solution, and the resultantsolution was diazotised by pouring, with stirring, into a mixture of 20cc. concentrated hydrochloric The diazonium solution was then added withcooling and stirring to a solution j of ethyl acetosuccinate A mol) in50 cc. of 20% acid and 100 gm. ice.

sodium hydroxide solution. After standing overnight the solution wasacidified and the dye filtered off and washed with water. Recrystallisedfrom. ethyl. alcohol it consisted ofa brick-red powder.

Melting point 224 C. with decomposition.

QEXQMPLE. 11-

P'repamtion of V 4-p-1iz'irobeitzeneazo-1-p nitrophenyl-fi-carbozcylicacid-5-pymeolone paNitraniline (iamol) was warmed with 35 cc.concentrated? hydrochloric acid and. the solution rapidly cooed. Thesuspension of the p-nitraniline hydrochloride was diazotised by adding asolution of sodium nitrite (1%. mol) in 30 cc. water. The diazoniumsolutionwas added to a solution of ethyl acetosuccinate 5 mol) in 50 cc.20% sodium hydroxide solution. After standing overnight the brownprecipitatewas filtered ofi andwashed. withwater. This was hydrolysed tothe free acid by boiling for 15 minutes with 10% sodium hydroxidesolution. The solution was filtered from impurity and the dye isolatedby acidification followed by filtration. Recrystallised from acetic acidit consisted of orangeyellow crystals. Melting point 260 C. withdecomposition.

EXAMPLE 12 Preparation of dye of the probable formula:

2 n'aplithylamine 4:8 disulphonic acid sodium salt mol) was dissolvedin100- cc. Water and sodium int-rite (es-m n added. Diazotisation was"effected by ;pouring*thesolution into a mixture oi ed cc. concentratedhydrochloric acid= 'and i'- 200 gm. ice. After standing for half an hourthe.

solution was added to a solution of ethyl acetosuccinate in 100 cc. 20%sodium hydroxide solution. The dye was isolated by salting out andobtained as reddish-brown crystals. Melting point above 260 C.

EXAMPLE 13 Preparation of dye of the probable unit structure:

CO CO 8 ExAuPLs 15' Preparation of dye of the probable unit structure: I

( 30002155 COOCzHs I Benzidine mol) was warmed with 25 cc. concentratedhydrochloric acid and cooled. An equal volume of water was then addedand the solution tetrazotised by the addition of a solution of sodiumnitrite mol) in water, with cooling and stirring. After half an hour thediazonium soluoo U I (w is an undetermined integer)1:5-diaminoanthraquinone 6 mol) Was heated with 60 cc. concentratedhydrochloric acid for half an hour. Then the suspension was cooled andtetrazotised by addition of sodium nitrite (/5 mol). The solution wasadded to a solution of ethyl aoetosuccinate mol) in 120 cc. 20% sodiumhydroxide solution. The precipitated dye was filtered oil and washedwith water. It was purified by boiling out with methyl alcohol, andobtained as a scarlet powder. Melting point 176C. with decomposition.

EXAMPLE 14 Preparation of dye of the probable formula:

Dehydrothio-p-toluidine 6 mol) was heated with 70 cc. 5 N hydrochloricacid and the solution rapidly cooled. It was diazotised by adding anaqueous solution of sodium nitrite mol). The suspension of the diazoniumsalt obtained was diluted with water and added to a solution of ethylacetosuccinate /10 mol) in 65 cc. sodium hydroxide solution. The dyeseparated from the reaction mixture and was filtered off and washed withwater. obtained as dark crimson crystals with a green reflex. Meltingpoint above 265 C.

After drying the dye wastion was added to a solution of ethylethaneaafi-tliCBJ'bOXYltte & mol) (Bischoff, Annalen, vol. 214, page 38)in 60 cc. 20% sodium hydroxide solution. After standing overnight thecrimson azo dye was filtered 01f and washed with water.

Melting point above 300 C.

The same dye may be obtained by substituting ethyl acetosuccinate forthe ethyl ethane-auritricarboxylate.

What we claim is:

1. 'A process for the production of azo dyestuiis which comprisesreacting a diazonium compound with a compound of the formula:

CHCH2-COOCzHt R:

where R1 and R2 are each selected from the class consisting of CN,-CO0H, -COOalkyl, -COalkyl, COary1, CONH2, -CONHalkyl, and CONHaryl, thesaid reaction with the diazonium compound being effected in the presenceof caustic alkali and the said diazonium compound being present in aproportion of at least two molecular equivalents per molecularequivalent of the compound of the aforesaid formula.

3. A process for the production of azo dyestuffs which comprisesreacting a diazonium compound with a compound of the formula:

CHCHa-C O Calls where R1 and R2 are each selected from the classconsisting of CN, COOH, COOalkyl, COalkyl, COaryl, CONl-Iz, CONHalkyl,and CONHaryl, the said reaction with the diazonium compound beingeffected in the presence of strong alkali and the said diazoniumcompound being present in a proportion of at least, two molecularequivalents per molecular equivalent of the compound of theaforesaidformula, and purifying the azo dye produced from any byproducts of thereaction. 1

4. A process for the production of azo dyestuffs which comprisesreacting a diazonium compound with ethyl acetosuccinate in strongalkaline solution, the diazonium compound being present in a proportionof at least two molecular equivalents per molecular equivalent of theethyl acetosuccinate.

5. A process for the production of azo dyestuffs which comprisesreacting a diazonium compound with ethyl acetosuccinate in causticalkali, the diazonium compound being present in a proportion of at leasttwo molecular equivalents per molecular equivalent of the ethylacetosuccinate.

6. A process for the production of azo dyestuffs 10 which comprisesreacting a diazonium compound with a compound of the formula:

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,792,355 Boeniger Feb, 10, 19311,880,225 Zinner Oct. 4, 1932 1,951,082 Bonhote Mar. 13, 1934 2,219,712Schmid Oct. 27, 1940 2,241,795 Taube May 13, 1941 2,366,616 HarringtonJan. 2, 1945 FOREIGN PATENTS Number Country Date 265,553 Great Britain HMar. 20, 1928

